1. Field of the Invention
The present disclosure relates to a magnetic contactor, and particularly, to an auxiliary contact mechanism that supplies electric power for magnetization to a magnetic coil for opening and closing a main contact in a magnetic contactor until immediately before the main contact is closed.
2. Background of the Invention
A magnetic contactor is a magnetic switch commonly used as a switch for supplying or cutting off electric power to generally run or stop control of an electric motor.
The magnetic contactor has the following operation principle. That is, according to magnetization of a magnetic coil, a stationary core accommodated within the magnetic coil attracts a moving core by magnetic force, and as the moving core is moved toward the stationary core according to the magnetic attraction, a movable contact supporting rod called a cross bar made of an electrical insulating material coupled to the moving core is moved together toward the stationary core and a movable contact comes into contact with a corresponding stationary contact to form a closing state such that a circuit is electrically connected
Such a magnetic contactor may include a main contact mechanism having a closing position (or ON position) in which the electric power is applied to an electrical load such as a motor and an opening position (or an OFF position) in which electric power supply to the electrical load is cut off, and an auxiliary contact mechanism configured as a normally close contact which supplies electric power to a magnetic coil of the main contact mechanism or cuts off electric power supply to the magnetic coil of the main contact mechanism.
An example of the related art with respect to the magnetic contactor will be described with reference to FIGS. 1 to 3 as follows.
As can be seen from FIG. 1, a magnetic contactor according to an example of the related art may be a magnetic contactor in which an auxiliary contact mechanism according to an embodiment of the present invention may be installed to be used instead of an auxiliary contact mechanism of the related art. The magnetic contactor according to an example of the related art will be described commonly with reference to the present invention.
As can be seen from FIG. 1, the magnetic contactor 100 according to an example of the related art includes a main contact mechanism and an auxiliary contact mechanism 30.
The main contact mechanism includes a main contact slide support member 10 and a magnetic coil 20.
The main contact slide support member 10 is a supporting member which may be coupled with a main movable contact, among a main stationary contact and a main movable contact having main contacts, that is, contacts, and slidably movable in a vertical direction together.
A vertical guide recess portion (not shown) may be provided on a side wall of an outer case (not shown) of the magnetic contactor 100 in order to guide and support a side wall portion of the main contact slide support member 10 such that it is slidably movable.
An auxiliary contact pressing portion 10a is integrally provided with the main contact slide support member 10 and extends from the main contact slide support member 10 toward the auxiliary contact mechanism 30.
The auxiliary contact pressing portion 10a is a portion of the main contact slide support member 10 which is lifted and lowered according to a vertical movement of the main contact slide supporting member 10 to a position in which it presses the auxiliary contact mechanism 30 or to a position in which it is apart from the auxiliary contact mechanism 30.
The magnetic coil 20 is configured as an electromagnet, that is, as a coil magnetized when an electric current flows on the magnetic coil 20. The magnetic coil 20 is installed in the vicinity of a stationary core (not shown) to form a magnetic coil assembly.
A movable core (not shown) may be provided in a position opposite an upper portion of the stationary core, and the corresponding movable core may be coupled to the main contact slide supporting member 10 and moved in a direction such that it approaches the stationary core or in a vertical direction such that it is apart from the stationary core.
In FIG. 1, reference numeral 40 denotes a coil assembly accommodation case as an outer case which accommodates the magnetic coil assembly of the main contact mechanism and the auxiliary contact mechanism 30.
A support wall portion (not shown) may be provided on an inner side wall of the coil assembly accommodation case 40 in order to support a contact support member 31 of the auxiliary contact mechanism 30 as described hereafter such that a position thereof is fixed.
Meanwhile, a detailed configuration and operation of the auxiliary contact mechanism 30 of the magnetic contactor according to an example of the related art will be described with reference to FIGS. 2 and 3.
The auxiliary contact mechanism 30 of the magnetic contactor according to an example of the related art includes a contact support member 31, a slide movable supporter 32, a stationary contact 33, a movable contact 34, an auxiliary contact spring 35, and a return spring 36.
The contact support member 31 provides a means for supporting the stationary contacts 33 among the auxiliary contact mechanism 30, and has an axial recess portion 31a formed extendedly at the inner side in a vertical direction from an upper surface to a blocked bottom surface to allow the slide movable supporter 32 to be vertically movable.
The contact support member 31 may be made of an artificial resin insulating material having electrical insulating characteristics, and may be fixedly supported by a support wall portion (not shown) provided in an inner side wall of the coil assembly accommodation case 40 of FIG. 1.
The slide movable supporter 32 is a means slidably lifted or lowered in a vertical direction through the axial recess portion 31a of the contact support member 31, and coupled to the movable contact 34 such that the movable contact 34 is inserted into a central portion and supported.
Each of the stationary contacts 33 is configured as an electrical conductor thin plate member formed to have an “L” shape, and includes a terminal portion protruded to be exposed from outer side of an upper portion of the contact support member 31 and a contact portion extending to the inner side of the contact support member 31 and having a contact in an end portion.
The stationary contacts 33 are configured as a pair and supported in the contact support member 31. One stationary contact 33 may be electrically connected with an external control electric power line (not shown) to open or close the magnetic contactor 100, and the other stationary contact 33 may be electrically connected with the magnetic coil 20 of the main contact mechanism.
The movable contact 34 may be configured as an electrical conductor thin plate member formed to have a shape of about a straight line shape and includes a support portion inserted to pass through a central portion of the slide movable supporter 32 and contact portions provided in both end portions of the movable contact 34 such that they face the contact portion of the stationary contact 33 and being movable in a vertical direction to a position in which the contact portion is in contact with the contact portion of the stationary contact 33 or separated from the contact portion of the stationary contact 33.
The auxiliary contact spring 35 is supported between a bottom surface of a central portion of the movable contact 34 and a spring support protrusion portion provided to be protruded upwardly from a lower portion of the slide movable supporter 32, and provides elastic force pressing toward the stationary contact 33 to the movable contact 34.
The return spring 36 is supported between a lower end portion of the slide movable supporter 32 and the spring support protrusion portion formed to be protruded upwardly from a bottom surface of the contact support member 31, and provides elastic force to the slide movable supporter 32 to move upwardly.
The operation of the auxiliary contact mechanism 30 of the magnetic contactor according to an example of the related art configured as described above will be described with reference to FIGS. 2 and 3.
An operation of the magnetic contactor to a circuit closing position (or an ON position) will be described.
When control electric power is supplied from the external control electric power line (not shown), the electric current flows between both stationary contacts 33 in a state that the movable contact 34 is in contact with the both stationary contacts 33 in the state of FIG. 2, and thus, the current from the control electric power flows to the magnetic coil 20 of FIG. 1.
Thus, the magnetic coil 20 is magnetized to attract the movable core (not shown) and the main contact slide support member 10 downwardly, so that a circuit closing position operation is executed that the movable contact (not shown) coupled to the main contact slide support member 10 comes into contact with a lower stationary contact (not shown).
Thus, the auxiliary contact pressing portion 10a integrally connected with the main contact slide support member 10 is lowered together with the main contact slide support member 10 to pressurize an upper end portion of the slide movable supporter 32 downwardly as shown in FIG. 3.
Thus, the slide movable supporter 32 and the movable contact 34 overcome elastic force of the auxiliary contact spring 35 and the return spring 36 and are moved together downwardly. At this time, the slide movable supporter 32 is slidably lowered through the axial recess portion 31a of the contact support member 31 as a lifting or lowering passage.
Thus, the movable contact 34 of the auxiliary contact mechanism 30 is separated from both stationary contacts 33, and thus, the supply of control electric power supplied to the main contact mechanism through the auxiliary contact mechanism 30 is cut off.
A circuit opening position (or an OFF position) of the magnetic contactor will be described.
When the supply of control electric power from the external control electric power line (not shown) is stopped, that is, when a control signal through the control electric power line is not provided, even though the movable contact 34 comes into contact with the both stationary contact 33 in the state illustrate in FIG. 2, there is no current from the control electric power flowing to the magnetic coil 20 in FIG. 1 because there is no current flowing through the both stationary contacts 33.
Thus, the magnetic coil 20 is demagnetized and magnetic attractive force attracting the movable core (not shown) and the main contact slide support member 10 downwardly disappears, and as the main contact slide support member 10 is moved upwardly by elastic force of the return spring (not shown), the movable contact (not shown) coupled to the main contact slide member 10 is separated from the lower stationary contact (not shown), thus performing a circuit opening position operation.
Thus, the auxiliary contact pressing portion 10a integrally connected with the main contact slide support member 10 is lifted together with the main contact slide support member 10, and pressure pressing an upper end portion of the slide movable supporter 32 downwardly disappears.
Thus, the slide movable supporter 32 and the movable contact 34 are moved upwardly together by elastic force of the auxiliary contact spring 35 and the return spring 36. At this time, the slide movable supporter 32 is slidably lifted through the axial recess portion 31a of the contact support member 31 as a lifting or lowering passage.
Thus, the movable contact 34 of the auxiliary contact mechanism 30 comes into contact with the both stationary contacts 33, and thus, next supply of control electric power toward the main contact mechanism through the auxiliary contact mechanism 30 is waited.
However, in the auxiliary contact mechanism of the magnetic contactor according to the related art configured and operated as described above, as soon as the auxiliary contact pressing portion 10a integrally connected with the main contact slide support member 10 pressurizes the slide movable supporter 32 of the auxiliary contact mechanism 30 downwardly, the movable contact 34 of the auxiliary contact mechanism 30 is separated from both stationary contacts 33. Thus, electric power supply to the main contact mechanism is stopped before an operation of the main contact mechanism to the circuit closing position (or ON position) is not completed, and thus, there is a problem of occurrence of the phenomenon that the operation of the main contact mechanism to the circuit closing position (or ON position) is not completed.